feat(ui): add roadblock reply field to the ROADBLOCK card

A task that reports a roadblock but finishes successfully (Done/WaitingForReview/
Failed/Cancelled) had no way to answer it short of a full reset-and-rerun, losing
the run's context. Adds a reply textbox + Send button to the existing ROADBLOCK
card, modeled on the AskUser question card, that resumes the session via
ContinueTaskAsync with the user's own text. Gated on LatestRunSessionId (disabled
with a hint when there's nothing to resume); failures surface through the footer
error strip instead of a modal.

src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml

@@ -78,6 +78,25 @@
               <SelectableTextBlock Text="{Binding Roadblocks}"
                                    TextWrapping="Wrap"
                                    Foreground="{DynamicResource TextDimBrush}"/>
+              <Grid ColumnDefinitions="*,Auto" ColumnSpacing="6">
+                <TextBox Grid.Column="0"
+                         Text="{Binding RoadblockReplyDraft, UpdateSourceTrigger=PropertyChanged}"
+                         PlaceholderText="{loc:Tr details.roadblockReply.placeholder}"
+                         IsEnabled="{Binding CanReplyToRoadblock}"
+                         AcceptsReturn="False">
+                  <TextBox.KeyBindings>
+                    <KeyBinding Gesture="Enter" Command="{Binding SendRoadblockReplyCommand}"/>
+                  </TextBox.KeyBindings>
+                </TextBox>
+                <Button Grid.Column="1"
+                        Content="{loc:Tr details.roadblockReply.send}"
+                        Command="{Binding SendRoadblockReplyCommand}"/>
+              </Grid>
+              <TextBlock Classes="meta"
+                         Text="{loc:Tr details.roadblockReply.noSession}"
+                         IsVisible="{Binding !CanReplyToRoadblock}"
+                         TextWrapping="Wrap"
+                         Foreground="{DynamicResource TextDimBrush}"/>
             </StackPanel>
           </Border>